The goals of the projected investigations include the development and comparison of three scaling techniques capable of yielding equal sensory distances (equal loudness differences). These employ discrimination methodology with animal subjects. Our basic assumption is that is reinforcement schedule effects are parceled out, or held constant, tonal differences yielding similar levels of differential responding (behavioral equivalents) define equal sensory distances. We expect to compare families of behavioral equivalents obtained using the same tonal differences when different pshychophysical methods are employed. For example, stimulus sets producing equivalent differential responding obtained using one technique would be compared with those obtained using another. The three experimental paradigms we plan to employ are: (1) Two valued auditory intensity method (3-ply multiple schedule). (2) Tonal change-no change method ("same" - "different" judgement) (3) Non- differential reinforcement of intensity pairs (differential responding attributable to stimulus intensity dynamism). Each method will be employed to derive several values to determine internal consistency. In addition, the three methods will be compared to establish the generality of the findings. An appropriate transformation relating physical intensity to perceived loudness will be sought, consonant with the equal sensory distances derived from our three equal differential response techniques. It is also planned to make species comparisons between rat and chinchilla run in comparable studies.